An e-mail from the school said: 'Shots fired. Campus on lockdown. Cops on the scene. Details to follow.'

A mass-notification system can mitigate various issues after a campus shooting happens, but it’s not going to stop the active shooter

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McKINNEY, Texas — A community college about 30 miles north of Dallas has been put on lockdown after reports of gunfire.

An e-mail alert, sent shortly after 9:30 a.m. Tuesday to students and staff of the Collin County Community College District, warned that shots had been fired and that the central campus in McKinney was closed.

The e-mail said: "Shots fired. Campus on lockdown. Cops on the scene. Details to follow."